The average car in the U.S. produces about 4.6 metric tons of carbon dioxide (CO₂) per year. However, a car's total pollution is a mix of tailpipe emissions and non-exhaust emissions, and the amount varies significantly based on the vehicle's fuel type, age, and how it's driven. To put that annual CO₂ figure in perspective, it's equivalent to the emissions from powering an average home for over six months.
The primary pollutant from gasoline engines is CO₂, a major greenhouse gas. But cars also emit other harmful substances:
- Nitrogen Oxides (NOx): Contribute to smog and respiratory problems.
- Particulate Matter (PM): Tiny particles that can penetrate deep into the lungs.
- Carbon Monoxide (CO): A poisonous gas.
- Hydrocarbons (HC): A precursor to ground-level ozone.
Modern emissions standards have drastically reduced pollution per vehicle. The key difference often lies in the vehicle's age and technology. The following table illustrates the annual tailpipe CO₂ emissions for different vehicle types, assuming an average annual mileage of 11,500 miles.
| Vehicle Type | Estimated Annual CO₂ Emissions (metric tons) | Key Factors |
|---|
| Average New Gasoline Car | 4.6 | Fuel economy (mpg) is the largest determinant. |
| Hybrid Electric Vehicle (HEV) | 2.5 - 3.5 | Regenerative braking and electric assist reduce fuel burn. |
| Battery Electric Vehicle (BEV) | 0 (Tailpipe) | Produces zero direct tailpipe emissions. |
| Large SUV / Truck | 6.5+ | Lower fuel efficiency leads to higher emissions. |
| 20-Year-Old Gasoline Car | 7.0+ | Older models lack advanced emission control systems. |
It's crucial to remember that electric vehicles (EVs) are not entirely emission-free. While they have zero tailpipe pollution, generating the electricity to charge them creates emissions, a concept known as well-to-wheel emissions. However, even when accounting for the U.S. electrical grid's energy mix, the total greenhouse gas emissions of a typical EV are significantly lower than those of a gasoline car. Beyond tailpipes, non-exhaust emissions from tire and brake wear also contribute to particulate matter pollution, an issue that affects all vehicles, including EVs.
